This research project is designed to study the biochemistry of alpha-D-galactopyranosyl units in animal glycoproteins. We shall investigate the mode of biosynthesis, biodegradation and possible biological significance of this relatively rare carbohydrate group. Our model system will be the Ehrlich ascites tumor cell, the membrane of which contains a family of glycoproteins with alpha-D-galactosyl end groups. Alpha galactosyltransferase activity has been localized in the microsomal fraction of an Ehrlich cell homogenate. The alpha-galactosyltransferase(s) will be purified and studied with regard to its (their) physicochemical and kinetic properties. Acceptor activity of the transferase(s) will be studied with a recently developed solid-phase assay system. Recently, we have identified the alpha-D-galactosyl-containing glycoprotein(s) which occurs on Ehrlich ascites tumor cells and on thioglycollate-stimulated murine peritoneal macrophages as laminin or a glycoprotein related to laminin, and which cross-reacts with rabbit antibodies raised to murine laminin. We are currently isolating the laminin for characterization.